Antisense-mediated therapeutic pseudoexon skipping in TMEM165-CDG

Area of Science:

• Biochemistry
• Genetics
• Molecular Biology

Background:

• Congenital disorders of glycosylation (CDG) are genetic diseases caused by defects in protein glycosylation, often leading to multisystem phenotypes.
• Current therapeutic options for most CDG types are limited, necessitating the development of targeted treatments.
• TMEM165-CDG is a newly identified CDG subtype characterized by a skeletal phenotype and Golgi apparatus dysfunction.

Purpose of the Study:

• To investigate the molecular basis of a novel CDG caused by a deep intronic mutation in TMEM165.
• To develop and validate an antisense oligonucleotide-based therapy for TMEM165-CDG.
• To demonstrate the potential of antisense oligonucleotide-mediated pseudoexon skipping for treating Golgi-related protein deficiencies.

Main Methods:

• Functional in vitro splicing assay using minigenes to identify the pathogenic mechanism of the c.792+182G>A mutation.
• Development of antisense morpholino oligonucleotides targeting TMEM165 mRNA.
• Treatment of patient-derived fibroblasts with antisense morpholino oligonucleotides to assess rescue of TMEM165 protein levels.

Main Results:

• The deep intronic variant c.792+182G>A was confirmed to cause aberrant exon insertion, leading to TMEM165 dysfunction.
• Antisense morpholino oligonucleotide therapy effectively corrected the splicing defect.
• Normal TMEM165 protein levels were restored in the Golgi apparatus of treated patient fibroblasts.

Conclusions:

• Antisense oligonucleotide therapy is a viable proof-of-concept treatment for TMEM165-CDG.
• This study expands the therapeutic application of antisense oligonucleotides to Golgi-resident proteins.
• Targeted antisense oligonucleotide therapy offers a promising personalized treatment option for TMEM165-CDG and potentially other genetic disorders.